Advances in electronic devices generally include reducing the size of the components that form integrated circuits. With smaller circuit components, the value of each unit area of a semiconductor wafer becomes higher. The planarization, contaminant count, and general uniformity of a semiconductor wafer become critical to achieving this reduction in size of integrated circuits and enhancing the performance of these integrated circuit devices.
In order to planarize a semiconductor wafer and to remove particle contaminants, many wafer manufacturer employ chemical mechanical polishing ("CMP") processes. CMP systems place a semiconductor wafer in contact with a polishing pad that rotates relative to the semiconductor wafer. The CMP process will reduce voids in the wafer, increase the flatness of the wafer, and generally will enhance the performance of the integrated circuit. To enhance the effectiveness and the life of the polishing pad, CMP systems typically employ a conditioning disk to condition the polishing pad. The conditioning disk will contact the polishing pad surface to condition the polishing pad to enhance the planarization of the polishing pad. Conventional pad conditioning systems typically dispense a slurry onto the polishing pad prior to the conditioning disk contacting the polishing pad. These conventional pad conditioning systems have several limitations.
One problem associated with conventional pad conditioning using conditioning disks involves particle damage to the wafer. The conditioning disk removes a relatively small layer of the polishing pad to condition the polishing pad. The particles removed from the polishing pad can contact the wafer during polishing and scratch or otherwise damage the wafer.
The conditioning disks can provide another source of particulate generation. The conditioning disks used in conventional pad conditioning systems typically have an abrasive surface. The particles from this abrasive surface, such as the diamonds and nickel used in diamond impregnated disks, can break away from disk onto the polishing pad during conditioning. This can lead to scratches on the wafer surface during wafer polishing that damage the wafer.
The slurry used in the polishing pad conditioning process can also cause problems. The slurry can contaminate voids in the polishing pad surface or impregnate into the polishing pad surface. The slurry can also create a glaze over the polishing pad surface. Both of these slurry-related problems can reduce the polishing pad's effectiveness, which in turn, can reduce the uniformity of the wafer. The slurry may also provide a source of particle contamination that can damage the wafer during polishing.